This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A158725 #8 May 13 2013 01:54:10 %S A158725 49,91,119,133,161,169,203,217,221,247,259,287,289,299,301,323,329, %T A158725 343,361,371,377,391,403,413,427,437,469,481,493,497,511,527,529,533, %U A158725 551,553,559,581,589,611,623,629,637,667,679,689,697,703,707,713,721,731 %N A158725 Non-repdigit composite numbers not divisible by 2, 3, 5 or 11. %C A158725 Non-repdigit composite numbers ending in 1, 3, 7 or 9, with digital root not a multiple of 3 and whose alternate digit sums do not differ by a multiple of 11. %C A158725 The "compositeness" of larger entries of the sequence is not obvious right away or deducible by mere inspection, and hence these terms readily lend themselves to be (erroneously) suspected as primes to the casual glance. %C A158725 This differs from the corresponding sequence without the repunit condition starting at a(1351) = 11123 rather than 11111. - _Charles R Greathouse IV_, Sep 08 2012 %H A158725 Charles R Greathouse IV, <a href="/A158725/b158725.txt">Table of n, a(n) for n = 1..10000</a> %F A158725 a(n) ~ kn with k = 33/8. - _Charles R Greathouse IV_, Sep 08 2012 %o A158725 (PARI) is(n)=gcd(n,330)==1&&!isprime(n)&&n%(10^#Str(n)\9) \\ _Charles R Greathouse IV_, Sep 08 2012 %Y A158725 Cf. A007775, A053795, A008364. %K A158725 nonn %O A158725 1,1 %A A158725 _Lekraj Beedassy_, Mar 24 2009 %E A158725 Corrected and extended by _Ray Chandler_, Mar 27 2009